A zoom lens system suitable for a film camera, an electronic still camera, and a video camera has been proposed (for example, Japanese Patent Application Laid-Open Nos. 2004-61910, and 11-174329).
However, conventional zoom lens system has a zoom ratio of about two, so that a requirement for a high zoom ratio cannot be sufficiently satisfied. Moreover, since the position of an aperture stop is not optimized, excellent optical performance cannot be accomplished.